In recent years, the research dedicated to the mobile communication devices is on the increase due to their portable convenience. It may be advantageous to combine two or more wireless techniques into one apparatus, system or method. However, a deficiency in combining two or more wireless communication techniques is that the transmission and reception of two wireless communication techniques may interfere with each other, especially when two or more wireless communication techniques operate within the same frequency band.
For example, both Bluetooth and WLAN protocols generally operate in the 2.4 GHz (2.4000-2.4835 GHz) Industrial, Scientific, and Medical (ISM) unlicensed band. Bluetooth is a frequency hopping protocol, while WLAN is working at a central frequency. If Bluetooth hops in a frequency same as WLAN's central frequency, WLAN's frame may be corrupted by Bluetooth's packet. On the other hand, Bluetooth's frame is also affected if it hops into WLAN's working channel. When Bluetooth and WLAN modules are collocated on a board, the scenario goes even worse because any one's transmission power may saturate the other's receiver via the board. Accordingly, IEEE 802.15.2 provides solutions to this problem. One of the mitigation schemes discussed in IEEE 802.15.2 is Packet traffic arbitration (PTA) scheme.
The PTA technique provides a time division multiplexing (TDM) approach. FIG. 1 shows an electronic apparatus 100 employing the PTA mechanism. As shown, a WLAN module 120 and a Bluetooth module 130 are collocated with each other. The WLAN module 120 includes an IEEE 802.11 MAC 122, which communicates with an IEEE 802.11 PLCP+PHY layer control block 124. The Bluetooth module 130 similarly includes an IEEE 802.15.1 LM+LC block 132, which communicates with an IEEE 802.15.1 baseband controller 134. A PTA controller 110 is provided to determine which of the WLAN module 120 and the Bluetooth module 130 will be allowed to transmit at a given moment. The PTA controller 110 includes a WLAN (802.11b) control part 112 and a Bluetooth (802.15.1) control part 114, and they receive current status information 144 and 154 from each of the WLAN module 120 and the Bluetooth module 130. When the WLAN module 120 intends to transmit, it sends a transmission request 140 to the WLAN control part 112 and waits for the WLAN control part 112 to reply with a transmission confirmation 142 before proceeding to the transmission. Similarly, when the Bluetooth 130 intends to transmit, it sends a transmission request 150 to the Bluetooth control part 114 and waits for the Bluetooth control part 114 to reply with a transmission confirmation 152 before proceeding to the transmission.
The existing implementation assumes that the WLAN module 120 provides Internet connectivity and the Bluetooth module 130 provides handset and earphone connection. Thus, the PTA 110 grants the transmission request of the Bluetooth module 130 solely relying on information from Bluetooth module 130 without consideration of the traffic characteristic of the WLAN module 120. Consequently, a Bluetooth's packet has higher priority than a WLAN's frame, and therefore will have to interrupt ongoing WLAN traffic and result in interference of the WLAN link.
FIG. 2 shows the architecture of a voice over Internet protocol (VoIP) application. The mobile device 200 includes a WLAN module 220, a Bluetooth module 230, and a processor 205 for associating the WLAN module 220 with the Bluetooth module 230. The WLAN module 220 connects to Internet 270 via an Access Point (AP) 260 under IEEE 802.11 protocol, and the Bluetooth module 230 communicates with a Bluetooth device 250 (such as a handset or an earphone) via the Bluetooth protocol. Since conversation between the mobile device 200 and a remote device (not shown) over the Internet is carried by the WLAN module 220 and the Bluetooth module 230 together, the frame of the WLAN module 220 is as important as the packet of the Bluetooth module 230.
In addition to the priority issue, the distributed nature of WLAN protocol may cause WLAN module 220 to fail to receive a packet from the AP 260 when the PTA grants the Bluetooth module 230 access to the shared medium instead of granting the WLAN module 220 access to the shared medium. For this issue, IEEE 802.11e specifies an unscheduled APSD power delivery mechanism. According to the unscheduled APSD mechanism, the WLAN module 220 notifies the AP 260 that it is going to enter a power-saving mode, and the frames arranged to be transmitted to the WLAN module 220 will be buffered in the AP 260 until the AP 260 receives a frame called “QoS data-typed frame” as notification that the WLAN module is granted to operate. Then, the AP 260 will transmit an acknowledgement (ACK) frame to acknowledge receipt of the QoS data-typed frame. As conventionally designed, the WLAN module 220 will keep active for the duration of a frame-exchange, i.e. the periods of the transmission of the QoS data-typed frame and the receipt of its acknowledgement. Therefore, after the duration of a frame-exchange expires, i.e. after the WLAN module 220 receives the ACK frame, the Bluetooth module 230 may be granted access of the shared medium and the WLAN module 220 will not be granted for access the shared medium. However, at this time, the AP 260 may start to deliver the buffered frames to WLAN module 260.
Therefore, it is desirable to provide an apparatus and a method to grant the utilization of a plurality of wireless communication techniques while reducing the interference among the plurality of wireless communication techniques.